Inhibited chlorite baths and method



ITED CHLG BATHS AND NIETHOD Wilhelm Waibel, Frankfurt am Main, Germany, assignor to Farbwerke Hoechst Aktiengesellschaft vormals Meister Lucius 8; Bruning, Frankfurt am Main Hochst, Germany, a company of Germany No Drawing. Filed Oct. 2, 1956, Ser. No. 613,364

Claims priority, application Germany Dec. 15, 1953 6 Claims. (Cl. 252102) This application is a continuation-inpart application of my co-pending application Ser. No. 474,607, filed December 10, 1954, now abandoned, on: Compositions Suitable for Diminishing the Formation of Chlorine Dioxide in Acid Chlorite Baths and a Method of Such Diminishing.

In working with aqueous acid solutions of chlorites a certain amount of chlorine dioxide always escapes from the baths and this constitutes a great danger and annoyance to the operatives. The escape of chlorine dioxide from acid chlorite baths gives rise to considerable technical difiiculties and attempts have been made to overcome this inconvenience by using suction and absorption devices. These expedients are highly expensive and the loss of valuable material is inevitable.

In order to diminish the amount of chlorine dioxide evolved from the chlorite baths, it has been proposed to add various substances, for example, peroxides, and prefer ably hydrogen peroxide, to the acid chlorite baths. This expedient involves an additional consumption of the costly bleaching agent. It is also known to add fluorine compounds, and preferably acid fluorides, such as ammonium difluoride, to the acid chlorite baths, in order to suppress the evolution of chlorine dioxide. Apart from the fact that these fluorine compounds do not constitute an adequate remedy, they have the further disadvantage that they attack refined steel as well as ceramic material which relatively resistant to the acid chlorine solutions. It is also known to inhibit corrosion when working with aqueous solutions of chlorites or chlorine dioxide in apparatus of refined steel, by adding nitrates, for example, ammonium nitrate to the baths.

Now I have found that the formation of chlorine dioxide in acid chlorite baths can be diminished by adding to the baths ammonium chloride, ammonium sulphate, ammonium chlorate or an ammonium salt of an aliphatic carboxylic acid of low molecular weight and a sulphonic acid and/ or carboxylic acid containing an aliphatic radical of high molecular weight interrupted by a carboxylic acid amide or carboxylic acid ester group or a salt of such acid of high molecular weight.

The proportions in which the above mentioned ammonium salts are to be added per litre of liquor may vary within wide limits. An addition of about 0.5 to about 2 grams per litre of liquor generally suffices. For reasons of economy a proportion within the range of about 0.6 to 1 gram may be used, although proportions smaller'or larger than those mentioned above, for example, 0.3 or 5.0 grams, may be added.

The proportions of the sulphonic acid and/or carboxylic acid, or the salts thereof, containing an aliphatic radical of high molecular Weight interrupted by a carboxylic acid amide or carboxylic acid ester group may also vary within wide limits. It is possible to add quantities equal to, inferior to or larger than the quantity of ammonium salt used. In many cases it is sufiicient to use about one fourth of the amount of ammonium salt. Normally, quantities will be used amounting to one fourth up to the equal amount by weightof ammonium salt used. In

" tities of the surface-active substances claimed. Somemethyl-amino acetic acid, hydroxymethaneor hydroxytimes, it is also suflicient to add inferior quantities; in some cases the amount can be reduced to about 3& of the quantity of ammonia salt used.

In addition to the substances mentioned above, there may also be added to the chlorite baths the additions customarily used for adjusting the pH-value, for example, hydrochloric acid, formic acid, acetic acid, oxalic acid, phosphoric acid, nitric acid, bisulphates such as sodium bi-' sulfate, acid ortho-phosphates, pyrophosphates, acid polymeric phosphates or mixtures of these acid compounds, and the like.

In order to avoid corrosion when working in apparatus of refined steel, it is of advantage to add acids of the oxides of nitrogen or salts thereof.

As sulfonic and/or carboxylic acids of high molecular weight there enter into consideration reaction products as are obtained for instance by causing fatty acids ofhigh molecular Weight i.e. such containing more than 8 carbon atoms on amino-sulphonic or aminocarboxylic acids of low molecular weight or on protein decomposition produts. Furthermore, there are to be mentioned the condensation products of the salts from the above-mentionedfatty acids and halogen-sulphonic acids or halogen-carboxylic acids. The products can also be obtained by causing fatty acid derivatives to act upon aliphatic hydroxycarboxylic acids of low molecular weight. Such 'compounds are disclosed, for instance, by Schwartz-Perry Surface Active Agents, 1949, pages 34-39, 94-97 and 102l03. There are mentioned for example the reaction products of fatty acids, particularly in the form of their chlorides, containing more than 8 carbon atoms, especial- 1y those containing 12-18 carbon atoms, as, for instance, lauric acid, myristic acid, palmitic acid, stearic acid, or oleic acid with amino acetic acid, taurine, methyltaurine,

ethane-sulfonic acid, tartaric'acid and the like, for instance lauryl-methyl-tauride, oleyl-methyl-tauride, myristyland palmityl-tauride, stearyl tauride, stearoxy-methane and stearoxy-ethane-sulphonic acid, laurylsarcoside,'

stearylsarcoside, stearate of tartaric acid obtained by reaction of stearic acid chloride in dry pyridine on tartaric acid, etc.

The invention also includes a solid composition suitable for diminishing the formation of chlorine dioxide in' group or a salt of such acid of high molecular weight:

Such a composition is stable, and provides a mixture of the ingredients in the appropriate relative proportions,

so that, when required for use, there can be prepared therewith an aqueous solution containing a suitable quantity of the composition.

In order to inhibit corrosion when Working with chlorite baths in apparatus made of refined steel, a salt of an acidof an oxide of nitrogen, advantageously sodium nitrate, may also be incorporated in the above composition. Such compositions are very stable.

As an alternative to solid compositions, the invention.

also provides concentrated aqueous solutions of the ingredients mentioned above. Such concentrated solutions are-also stable. For use they need only be diluted with an appropriate quantity of water.

Patented Aug. '2, 19.60

In general,

percent. Bythe same procedure, using 0.6

gram per liter of ammonium nitrate, instead of am- 1nonium acetate, 0.32 percent of sodium chlorite was consumed, i.e. about 27 percent more than with the use 7 portions thereof may vary wide limits. .By increasing 'the quantities of the additions the rate of bleaching can be substantially reduced as required, and it is possible to work without any production of odour and also a substantial saving of chlorite can thus be achieved.

Example 5 A fabric of staple fibers of viscose was treated for 40 minutes at 75 C. at a goods-to-liquor ratio of 1:20 with a solution containing, per liter, 1 gram of sodium chlorite, 2 grams of ammonium nitrate, 5 grams of ammonium sulphate and 0.2 gram of oleyl-methyl-tauride and having a pH value of 3.5, adjusted by addition of mono-sodium phosphate and then rinsed. The material thus bleached had a whiteness of 79.8 percent. The consumption of sodium chlorite was not more than 0.18 percent. No liberation of chlorine dioxide occurred. Instead of the aforesaid quantity of ammonium sulphate, the same quantity of ammonium chloride or ammonium acetate may be used.

The above-mentioned quantities of surface-active agents and ammonium sulphate and also the relative proportions thereof may vary within widelimits. By increasing the quantities of the additions the rate of bleaching can be substantially reduced as required, and it is possible to work without any production of odour and also a substantial saving of chlorite can thus be achieved.

Example 6 A fabric of staple fibers of viscose was treated for 40 minutes at 75 C, at a goods-to-liquor ratio of 1:20 with a solution containing, per liter, 1 gram of sodium chlorite, 0.3 gram of ammonium chloride and 3 grams of lauryl-methyltauride and having a pH value of 3.5 adjusted by addition of formic acid, and then rinsed.

The material thus bleached had a whiteness of 80.2 percent. The consumption of sodium chloride did not exceed 0.21 percent. No chlorine dioxide escaped during the bleaching process. Instead of the aforesaid quantity of ammonium chloride, the same quantity of ammonium sulphate, ammonium chlorate or ammonium acetate may be used.

. Example 7 Knit goods of staple fibers of cellulose acetate were treated for 20 minutes at 70 C., at a goods-to-liquor ratio of 1:25, with a solution containing per liter 1.5 grams of calcium chlorite, 0.4 gram of ammonium chloride and 2 grams of lauric acid methyl tauride, as well as 1 gram of stearic acid sarcoside. The pH value of ,the bleaching bath was adjusted to 3.0 by means of a (mixture consisting of sodium acetate and hydrochloric acid in a proportion of 1:1.

During the bleaching process no escaping of chlorine dioxide was observed. An excellent bleaching result was obtained. The bleached knit goods were of agreeable handle.

Example 8 Yellowed yarn of polyamide fibers consisting of hexamethylene diarnine and adipic acid were treated for 1 7 Example 9 A fabricof polyester fibers from polyethylene glycol terephthalate was treated in a goods-to liquor ratio of 1:30 with a solution containing per liter 2 grams of sodium chlorite, 3 grams of ammonium phosphate, 2 grams of a condensation product of fatty acids of tallow and hydrolized protein and 1 gram of acid sodium hexa- -methaphosphate and adjusted to a pH value of 2 .5 by

the addition of nitric acid. The bleaching processwas carried out at 80 0. within 20 minutes. Then the fabric was rinsed and dried. An annoyance 'by escaping chlorine'dioxide was not observed when realizing the process in this way. A very satisfactory bleaching eifect was obtained.

'I claim:

1. A method of diminishing the formation of chlorine dioxide in acid sodium chlorite baths used for bleaching textile materials and having a pH of about 2.5 to 4.5, comprising adding to said baths an ammonium salt selected from the group consisting of ammonium chloride, ammonium sulphate, ammonium chlorate and ammonium acetate in a concentration of about 0.3 to 5 grams per liter and fiurther adding a compound selected from the group consisting of sulfonic acids and carboxylic acids containing an aliphatic radical having eight to eighteen carbon atoms which is interrupted by 'a carboxylic amide group and of sulphonic acids and carboxylic acids containing an aliphatic radical having eight to eighteen carbon atoms which is interrupted by a carboxylic ester group and the salts thereof.

2. A method of diminishing the formation of chlorine dioxide in acid sodium chlorite baths used for bleaching textile materials and having a pH of about 2.5'to 4.5, comprising adding to said baths ammonium chloride in a concentration of about 0.3 to 5 grams per liter and further adding the sodium salt of a sulfonic acid containing an aliphatic radical having eight to eighteen carbon atoms which is interrupted by a carboxylic amide group.

3. A method of diminishing the formation of chlorine dioxide in acid sodium chlorite baths used for bleaching textile materials and having a pH of about 2.5 to 4.5,

comprising adding to said baths ammonium sulphate in g a concentration of about 0.3 to 5 grams per liter and further adding the sodium salt of a sulfonic acid containing an aliphatic radical having eight to eighteen carbon atoms which is interrupted by a carboxylic amide group.

4. A method of diminishing the formation of chlorine dioxide in acid sodium chlorite baths used for bleaching textile materials and having a pH of about 2.5 to 4.5, comprising adding to said baths ammonium chlorate in a concentration of about 0.3 to 5 grams per liter and further adding the sodium salt of a sulfonic acid containing an aliphatic radical having eight to eighteen carbon atoms which is interrupted by a carboxylic amide group.

5. A method of diminishing the formation of chlorine dioxide in acid sodium chlorite baths used for bleaching textile materials and having a pH of about 2.5 to 4.5,

concentration of about 0.3 to 5 grams per liter and further adding the sodium salt of a sulfonic acid containing an aliphatic radical having eight to eighteen carbon atoms which is interrupted by a carboxylic amide group.

6. In the bleaching of a textile material by immersion in an aqueous solution of acid sodium. chlorite having a pH of about 2.5 to 4.5, the improvement which comprises carrying out the bleaching operation in the presence of an ammonium salt of the group consisting of ammonium chloride, ammonium sulfate, ammonium chlorate and ammonium acetate in a concentration of about 0.3 to 5 grams per-litre and a compound of the group consisting of sulfonic acids and the carboxylic acids containing an aliphatic radical having eight to eighteen carbon atoms which is interrupted by a carboxylic amide 7 group and of sulfonic acids and carboxylic acids containing an aliphatic radical having eight to eighteen carbon atoms which is interrupted by a carboxylic ester group and the salts thereof.

References Cited in the file of this patent 1 UNITED STATES PATENTS Hampel July 18, 1944 Riggs et a1. Feb. 11, 1947 10 

1. A METHOD OF DIMINISHING THE FORMATION OF CHLORINE DIOXIDE IN ACID SODIUM CHLORIDE BATHS USED FOR BLEACHING TEXTILE MATERIALS AND HAVING A PH OF ABOUT 2.5 TO 4.5 COMPRISING ADDING TO SAID BATHS AN AMMONIUM SALT SELECTED FROM THE GROUP CONSISTING OF AMMONIUM CHLORIDE, AMMONIUM SULPHATE, AMMONIUM CHLORATE AND AMMONIUM ACETATE IN A CONCENTRATION OF ABOUT 0.3 TO 5 GRAMS PER LITER AND FURTHER ADDING A COMPOUND SELECTED FROM THE GROUP CONSISTING OF SULFONIC ACIDS AND CARHOXYLIC ACID CONTAINING AN ALIPHATIC RADICAL HAVING EIGHT TO EIGHTEEN CARBON ATOMS WHICH IS INTERRUPTED BY A CARBOXYLIC AMIDE GROUP AND OF SULPHONIC ACID AND CARBOXYLIC ACIDS CONTAINING AN ALIPHATIC RADICAL HAVING EIGHT TO EIGHTEEN CARBON ATOMS WHICH IS INTERRUPTED BY A CARBOXYLIC ESTER GROUP AND THE SALTS THEREOF. 